Modulational instability of ion-acoustic soliton in electron-positron-ion plasma with dust particulates

Theoretical investigation has been made to study the envelope excitations of ion-acoustic solitons (IAS) in plasma composed of electrons, positrons, ions and dust particles. A nonlinear Schrödinger equation which describes the modulational instability of the IAS is derived by using the multiple scale method. The dispersive and nonlinear coefficients are obtained which depend upon the temperature of the ions, concentration of the positrons, electrons and dust particles. The modulationally stable and unstable regions are studied numerically for a wide range of parameters. It is found that these parameters play significant role in the formation of bright and dark envelope solitons in this plasma system.